Artificial arm



Feb. 6, 1951 G. M. MoTls ARTIFICIAL ARM 2 Sheets-Sheet 1 Filed Nov. 3, 1947 [N1/avro@ G-/Lfr M. M0775, JM/gw@ Arron/ver.

.wh QN ,QN NNN NNN vw N wm Y v. /v l. w N un. man vm N MW vm n w QM. QQ :w Q a., www waff m QN NN G. M. MOTIS ARTIFICIAL ARM Feb. 6, 1951 2 Sheets-Sheet 2 Filed Nov. 5, 1947 a y. n., @m w. ma M a 0,. .M M. .H T Ww 1 fm, j a .5w ,w y 4f; a y., M@ n. ,fi w 0,7 w 9J @M4 @of 6 1M Patented Feb. 6, 1951 ARTIFICIAL ARM Gilbert M. Motis, Burbank, Calif., assignor to Northrop Aircraft, Inc., Hawthorne, Calif., a corporation of California Application November 3, 1947, Serial No. 783,689

Claims.

The present invention relates to artificial arms, and the primary object of the invention is to provide an arm having a rotatable wrist unit which is coupled to the upper arm component so that when the,forearm is raised, the driven member of the wrist unit is automatically turned, and which is constructed and arranged so that such rotation of the driven member causes the hook or hand mounted thereon to move in a manner combining the motions of supination, flexion, and abduction.

The principal purpose for which the invention was developed is to provide improved facility in eating, since the act of raising a fork or spoon from the table to the mouth requires a combination of supination, iiexion, and abduction to hold the utensil level and turn the same into the mouth. In all prior arms having rotatable wrist units which are turned by forearm exion, the only motion provided has been that of supinaan angle to the forearm axis so that a spoon tion, which is inadequate for the manipulation of eating utensils, since it necessitates raising the elbow to an awkward level in order to provide the angular adjustment of the hook normally accomplished in the natural hand by abduction of the wrist, and also requires swinging the elbow forwardly in order to provide the angular motion normally accomplished by flexion of the wrist.'

in certain prior arms, attempts have been made to improve facility in eating by providing for passive or manual flexion adjustment of the wrist, so that the utensil is turned in toward the mouth without having to swing the elbow forwardly. However, practical considerations dictated the location of the flexion axis ahead of the supination axis, and the resulting coupled rotation causes the hook or hand to swing the utensil outwardly in an arcuate path about the supination axis, spilling the food contained therein, unless the elbow is raised simultaneously to hold the utensil in a level position. The reason for this will become immediately apparent when it is considered that a plane passing through the top edge of a spoon held in the hook has a xed angular relation to the supination axis which, for all practical purposes, may be treated as the forearm axis. Thus, if the forearm axis is horizontal when the spoon is held level at table height, it will also need to be horizontal when the spoon is raised to the mouth, which means that the elbow must be raised to the level of the mouth. This is an awkward position, and is objectionable to the amputee because it calls attention to his handicap. Y f

In the present invention, the axis of rotation detail of the driving mechanism, taken of the wrist unit driven member isdisposed at held in the hook ismaintained level, both at table height when the forearm is substantially horizontal, and when raised to the mouth, with the forearm at a natural angle. In addition-to providing improved facility in eating, the present invention enables the amputee to perform other acts such Ias smoking, shaving, and the like, wherein the hook is raised to face level, with greater ease and a more natural arm motion.

The foregoing and other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment thereof, reference being had to the accompanying drawings, in which:

Figure 1 is a partially cut away perspective view of an artificial arm embodying the principles of the invention, showing the arm in the extended position;

' Figure 2 is a similar view of the same, showing the forearm member flexed with respect to the upper arm component;

Figure 3 is a partially cut away top plan view of the arm;

Figure 4 is a` vertical section, taken along the line rl-l in Figure 3;

' Figure 5` is an enlarged perspective view. of the linkage for turning the wrist unit driven member about its axis of rotation; and

Figure 6 is an enlarged sectional view of a lalong the line 6 6 in Figure 3.

In the drawings, the reference numeral l0 designates the artificial arm in its entirety, said arm. comprising an upper arm component Il, to which a forearm member I2 is connected by an elbow hinge i 3. Mounted on the outer end of the forearm member l2 is a, wrist unit `lffl having an attach plate I 5 which is provided with means for detachably receiving a hook unit i6. In therembodiment illustrated, the upper arm component l consists' of a stump socket 20 which is preferably made up of laminated plastic-impregnated fabric, formed to receive the stump in a snug-fitting engagement; the lower end of the socket 20 being molded over and bonded to an annular flange 2| projecting rearwardly from a housing 22 forming a part of the elbow hinge unit i3. The elbow unit I3 is the same as that disclosed in the copending application of Meyer Fishbein et al., Serial No. 747,690, filed May 13, 1947, now Patent Number 2,537,338, to which reference may be had for details of construction and operation.

The housing 22 is generally cylindrical in shape, with a spherically curved outer end portion, and flats 23 at opposite sides thereof. A saddle 2li is mounted on the upper end of the forearm member i2 and has two laterally spaced ears 25 which are disposed to lie against the flats 23. Extending through the housing 22 and journalled in suitable bearings therein, is a hinge pin 26, the ends of which project from the flats 23 and are rigidly connected to the ears 25 by serrated plugs 3i?. Inside the housing 22 is a locking device (not shown) for locking the forearm member in any one of a large number of closely spaced angular positions relative to the upper arm component i i, and projecting through a slot 3l in the housing is a pivoted elbow lock lever 32 which is operatively connected to the locking device to actuate the same. A control wire 33 is connected to the outer end of the lever 32, and is attached at its upper end to one of the straps of the shoulder harness, so that the locking device can be locked and unlocked by alternate shrugs of the shoulder.

The saddle 25 consists of a conically tapered shell which embraces the bottom half of the housing 22 and is cut out at 34 to provide clearance for the housing when the forearm member is flexed, as shown in Figure 2. Below the cut out opening Se is a cylindrical collar 35 which is inserted over and riveted to the top end of a tube 35 forming the load-carrying structure of the forearm member l2. A forearm lift lever 40 is attached to the outer side of the saddle 2@ adjacent the rear end thereof, and projects upwardly and forwardly therefrom. A pull cord 4I is passed through a hole in the outer end of the lift lever :l5 and is knotted on the other side at 472 to keep it from pulling through the hole. The cord 5l extends upwardly along the outside of the arm through suitable guide loops, and is attached at its upper end to the shoulder harness, whereby the forearm member can be raised by a shrug of the shoulder.

The outer end of the forearm tube 35 extends over an annular shoulder 43 projecting rearwardly from the back of an end bearing cap member Lili, which forms the stationary member of the wrist unit i4, and is secured thereto by a plurality of countersink screws 55. ,Interposed between the inner surface of the tube 35 andy the shoulder i3 is a collar t5 having a cylindrically curved plate i9 projecting axially from a portion of its back edge up into the tube 35. The plate 49 lies against the inner surface of the tube 35 and forms a bell crank hinge bracket which supports certain parts of the drivingV mechanism, to be described presently.

Extending through the center of the bearing cap 54 at an angle to the axis, or centerline, of the forearm member i2 is an upwardly and inwardly inclined, threaded bore 55. The angle formed by the inclination of the axis of the bore 50 to the forearm centerline may be any angle in the neighborhood of from to 20, which I have found by experiment to be about the practical limit for most effective operation, although these limits are not to be taken as restrictive, in any sense, since they might be exceeded in either direction without departing from the scope of the invention. I have found, however, that if an angle of less than 10 is used, the amount of iiexion and abduction obtained is inadequate for most purposes, while an angle of greater than 20 introduces certanstructural difficulties in the design of the wrist unit and driving mechanism therefor. In the preferred form of the invention, the axis of the bore 50 is also inclined inwardly toward the body to an angle of approximately 45 to a plane passing through the forearm centerline and the axis of the elbow hinge pin 26. Or, expressed in another way, a plane passing through the axis of the bore 50 and the forearm centerline is inclined 45 to the axis of the elbow hinge pin 26. One other important relationship that should be observed is that the inclined axis of the bore 5B is flexed about the flexion-extension axis of the wrist unit, and is abducted about the abduction-adduction axis thereof.

The outer face of the cap Li is cut off perpendicular to the bore 5t, and is counterbored to receive a. washer 5i which cooperates with a cylindrical sleeve 52 to form the inner race for a rear row of ball bearings 53. The sleeve 52 is threaded on its rear end and is screwed into the threaded bore 5l); the front end of the sleeve projecting forwardly beyond the outer face of the cap 44. A radially outwardly turned flange 54 on the front end of the sleeve 52 cooperates with the cylindrical outer surface thereof to form an inner race for a front row of ball bearings 55. The outer race for both rows of ball bearings 53 and 55 is formed by an annular ring 56 having conical faces on both sides thereof, against which the balls 53- and 55 bear. The ring 55 is threaded on its outer surface and isA screwed into a threaded bore 6G `formed in the back end of a wrist unit driven member 6 l.

The bore 60 is concentric with the bore 50 in the` cap 44, and therefore bears the same angular relation to the forearm centerline as the latter bore. The rear face of the driven member 6| is cut olf perpendicular to the bore 6E), and is disposed closely adjacent to the front face of the cap 44. The outer surface of driven member 6I is cylindrical, and the axis thereof is inclined to the axis of the bore @il at the same angle as that dened between the axis of bore 5t and the forearm centerline. Preferably, although not necessarily, the angular relationship between the axes of the cylindrical outer surface of the driven member BI and the bore 55 is such that when the forearm is fully extended, the axis of the cylindrical outer surface is substantially parallel to the forearm centerline, and when the forearm is flexed, the driven member El is turned by the driving means, which will be described later, so that its axis is inclined to the forearm centerline at an` angle somewhat greater than the angle of the bores 55, 6G thereto. The purpose of this arrangement is to increase the amount of flexion and abduction obtained with a given amount of supination, over that which would be obtained solely by virtue of the inclination of the axis of rotation.

At' the front end of the wrist unit driven member 6i is an inwardly turned flange E2 which is received within an annular groove 53 formed in the back surface of the attach plate l5. The attach plate is secured to the member 6I by means of a clamping ring 64 having oppositely extending shoulders which engage the inside surfaceof the ange 62 andthe inner margin of the groove B3, respectively; said clamping ring being secured to the attach plate by means of suitable screws (not shown). Formed integrally with the attach plate I5 and projecting rearwardly from the back side thereof through the center of the bearingl race sleeve 52 'is a tubular extension 65 havingt a central bore 66 formed therein. A cylindrical coupling member 1D is slidably disposed within the bore 66, and formed in the outer end thereof is a socket 1I which is adapted to receive a companionate coupling member on the hook unit I6, to provide an operating connection therewith.

The hook unit I8 is adapted to be detachably mounted on the outer face of the attach plate I5, and is provided with a housing 12 having a flanged, vertically extending coupling plate 13 on its back face which is adapted to be inserted down into companionate ways 14 formed in the end of the attach plate I5. A hook control coupling member (not shown) projecting from the `back of the plate 13 seats in the socket 1I of the coupling member 1D as the housing 12 approaches full seating engagement with theattach plate I5, and the said coupling members are thereafter connected together and move as one. The coupling member on the unit I6 is operatively connected to a pivoted hook 15, and causes the latter to be closed against a stationary hook 16 `when the interconnected coupling members are moved axially toward the right in the bore 86. The mechanism for actuating the pivoted hook 15- forms no part of the present invention, and therefore need not be described in further detail.

The coupling member is urged `to the left by a compression spring 88 which is disposed within the bore 66 and bears against a radial iiange BI at the end of a tubular fiber bushing 82. The bushing 82 is pressed into a reduced bore 83 in the end of the tube 65, and the flange Si abuts against the shoulder formed at the junction of bores 83 and B6.

The coupling member 18 is adapted to be pulled to the right against the pressure of spring 88 to close the movable hook against the stationary hook 18, by means of a control wire 84 which extends through the center of the bushing 82 and spring 88, and into the back end of the member 1D, to which it is attached in any suitable manner. The control wire 84 extends up into the forearm tube 35 and has a fitting 85 soldered to its upper end. The iitting 85 is drilled to receive a pin 8S projecting laterally from one side of a cable pulley 90 which is journalled on a shaft 9i extending horizontally from a supporting bracket 92. The bracket 92 is curved to conform to the inside surface of the tube 36 and is attached thereto by screws or other suitable fastening means. A hub 93 projects from the other side of the cable pulley 90 to the bracket 92, and encircling this hub is a torsion spring 94, one end of which is attached to the bracket 92, and the other being attached to the hub 93. Projecting from the inside surface of the pulley 90 and concentric therewith is a smaller pulley 95, around Vwhich the wire 84 is trained when the pulley 93, 95 is rotated in a counterclockwise direction. Such counterclockwise rotation of the pulleys causes the wire 34 to be pulled to the right, causing the movable hook 15 to close against the stationary hook 16.

The cable pulley 98 is made to turn in a counterclockwise direction by means of a Bowden cable control wire 96, having a spring wound housing 55 which is threaded through a tapped hole in the outer side wall of the saddle 24 below the hinge pin 28. The upper end of the wire 96 is attached to one of the straps of the shoulder harness in the usual manner, so that when the harnessed shoulder is shrugged forwardly, the wire is pulled through the housing IUI). The

lower end of the wire 9B enters the groove Vof vsion to the arm.

the pulley 98 at the bottom thereof and is trained around the pulley in a clockwise direction. A ball fitting I8I is soldered to the end of the wire 95 and is seated in a socket |82 in the pulley 95 to secure the wire thereto. When the control wire 95 is pulled, the pulley 90 is rotated in a counterclockwise direction, causing the wire 84 to be wound up onto the smaller pulley 95. The tensile force in the -wire 96 is multiplied in the wire 84 by an amount equal to the ratio of the radius of the large pulley 90 to that of the small pulley V95, with a corresponding reduction in travel of wire 84.

The wrist unit driven member 6I is turned on its axis of rotation by driving means which will now be described. In the embodiment illustrated, the driving means is preferably in the form of a push-pull drive tube I which is connected at one end by a system of linkage to the tube 55 on the attach plater I5, and is connected at the other end by a drive yoke HB6 to the elbow housing 22 on the upper arm component II.

The yoke Illia is generally U-shaped in plan form,

and its ends are connected by pins IEN to the housing 22 at a point spaced outwardly from the hinge pin 28. Projecting forwardly from the bight portion of the yoke |86 to one side of the centerline thereof are two vertically spaced ears H33, and disposed between these ears is a bifuroated end member |89 which is pivotally connected to the ears H38 for horizontal swinging movement by means of a pin I I8. Extending forwardly from the member E89 is a threaded stem i i I which is screwed into the end of the tube I 85.

The opposite end of the drive tube I85 is solid, as shown in Figure 6, and is drilled axially at I I2 to form a socket for a ball member H3. The outer end portion of the hole II2 is screwthreaded to receive a screw plug II4, the inner end of which is formed with a spherical Seat I I5 which bears against the ball i I3. A keyhole slot IES in the bottom wall of the tube provides an opening through which the ball H3 can-be inserted into the socket H2, and through which the sha-nk I2@ of the ball member projects. The shank IZil of the ball imember is formed with a downwardly facing shoulder l2i, and projecting from this shoulder is a threaded stud |22 which extends through a hole in the outer end of a bell crank arm I23. A nut I24 is screwed onto the projecting bottom end of the stud E22, and draws the shoulder B2i tightly against the top of the bell crank arm E23, clamping the ball member rigidly to the arm.

The bell crank arm I2?. projects laterally from a hub I 25 and moves in a plane substantially parallel to the plane of the forearm centerline and elbow hinge axis. The hub ii is disposed between a raised boss E25 on the bottom of the plate 45, and `a lug IBS projecting laterally7 inward from the side thereof. A pin iti extends downwardly through aligned holes in the lug I3, hub H25, and boss 25, providing a pivot support for the bell crank. The other arm of the bell crank is shown at I32 and projects forwardly 'from the hub I25,y being considerably shorterin length than arm 23. Pivotally connected by a horizontal pin 33 to the bell crank arm I 32 is a link |34 which functions as a jointed exten- A socket 35 is formed in the top of the link 34 adjacent the outer end thereof, and confined within this socket is a ball I36 ,.the'link I48iis disposed between twdlaterally spaced arms 14| projecting rearwardly from a split clamp |42 mounted on the rear end of the tube 65. The link |40 is connected to the arms IM by a transverse pin |43 which permits swinging movement of the link |46 in a plane parallel to the axis of the tube E and offset slightly to one side thereof. The clamp |42 is secured on the tube 65 by means of a screw |44 which extends through aligned holes in two outwardly turned, vertically spaced ears |45, said screw being threaded into the bottom ear so that when the screw is turned down, the ears are drawn together.

The purpose of the several links in the system just described is toprovide means for accommodating the different paths taken by pin E33 on the bell crank, and pin |1l3 on the clamp member |42. Pin |63 travels in a circular path described in a plane perpendicular to the inclined axis of rotation of the wrist unit driven member 6|. Pin |33, on the other hand, travels in a circular path described in a substantially hori- Zontal plane, perpendicular to the bell crank pivot pin |31. The pivcted links |34 and |40, and the ball and socket connection |35, |36 accommodate this divergence of paths, and enable the drive tube |05 to rotate the wrist unit driven member iii about the latters inclined axis. A driving mechanism constructed as described above is capable of rotating the wrist unit driven member through an angular distance of as much as 90 responsive to an angular movement between the forearm member and upper arm component of approximately 130.

The manner in which the arm works is believed to be self-evident from the foregoing description When the forearm member I2 is fully extended, the wrist unit driven member 6I is turned so that the attach plate l5 is substantially perpendicular to the forearm centerline, with the hook unit i6 positioned in its normal relationship to the forearm, as shown in Figure l. As the forearm is raised in iiexion, the driving mechanism acts to turn the driven member 6| about its inclined axis of rotation, so that when the forearm is fully flexed, as in Figure 2, the wrist member 6| and hook unit |55 are turned in a manner combining the motions of supination, exion, and abduction. This combination of motions enables the amputee to hold a spoon level while raising the same from table level to the mouth, and also turns the spoon inwardly toward the mouth in a natural manner. As the forearm is lowered or extended, the driving mechanism acts to return the hook unit to its initial, or normal position.

While I have shown and described in considerable detail what I believe to be the preferred form of my invention, it is to be understood that such details are merely illustrative, and that various changes may be made in the shape and arrangement of the several parts without departing from the scope of the invention as defined in the appended claims.

I claim:

l. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge connecting said forearm member to said upper` arm component, a wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member mounted for rotation about an axis disposed at an angle of between 10 and 20 to the forearm centerline, an attach plate fixed to said Wrist unit driven member and adapted to receive a hook or hand on the outer face thereof, the plane of said outer face being disposed at the same angle to said axis of rotation as said axis frms with said forearm centerline, said attach plate being positioned so that the plane of said outer face is substantially perpendicular to said forearm centerline when said forearm is fully extended, and means connected to said upper arm component for rotating said wrist unit driven member responsive to flexion of said forearm member with respect to said upper arm component.

2. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge connecting said forearm member to said upper arm component, a wrist unit mounted lon the outer end of said forearm member, said wrist unit including a driven member mounted for rotation about an axis disposed at an' acute angle to the centerline of said forearm member, said axis being flexed about the flexion-extension axis of said wrist unit, and being abducted about the abduction-adduction axis thereof, an attach plate fixed to said wrist unit driven member and adapted to receive a hook on the outer face thereof, the plane of said outer face being disposed at the same angle to said axis of rotation as said axis forms with said forearm centerline, said attach plat-e being positioned so that the plane of said outer face is substantially perpendicular to said forearm centerline when said forearm is fully extended, a tube extending rearwardly from the back of said attach plate perpendicular to said outer face, said tube extending through said wrist unit and intersecting said axis of rotation, a hook control coupling device disposed within said tube and having a rearwardly extending force-transmitting member attached thereto, said coupling device being adapted to engage an actuating member on said hook, and means connected to said upper arm component for rotating said wrist unit driven member responsive to flexion of said forearm member with respect to said upper arm component.

3. An artiiicial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge connecting said forearm member to said upper arm component, a wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member mounted for rotation about an axis disposed at an angle of between 10 and 20 to the forearm centerline and lying in a plane inclined at an angle of approximately 45 to the axis of said elbow hinge, an attach plate fixed to said wrist unit driven member and adapted to receive a hook on the outer face thereof, the plane of said outer face being disposed at the same angle to said axis of rotation as said axis forms with said forearm centerline, said attach plate being positioned so that the plane of said outer face is substantially perpendicular to said forearm centerline when said forearm is fully extended, a tube extending rearwardly from the back of said attach plate perpendicular to said outer face, said tube extending through said wrist unit and intersecting said axis of rotation, a hook control coupling device disposed within said tube and having a rearwardly extending force-transmitting member attached thereto, said coupling device being adapted to engage an actuating member on said hook, and means connected to said upper arm component for rotating said wrist unit driven member responsive to flexion of said forearm member with respect to said upper arm component.

4. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge connecting said forearm member to said upper arm component, a wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member mounted for rotation about an axis disposed at an angle of between and 20 to the forearm centerline and lying in a plane inclined at an angle of approximately 45 to the axis of said elbow hinge, an attach plate xed to said wrist unit driven member and adapted to receive a hook on the outer face thereof, the plane of said outer face being disposed at the same angle to said axis of rotation as said axis forms with said forearm centerline, said attach plate being positioned so that the plane of said outer face is substantially perpendicular to said forearm cenerline when said forearm is fully extended, a tube extending rearwardly from the back of said attach plate perpendicular to said outer face, said tube extending through said wrist unit and intersecting said axis of rotation, a hook control coupling device disposed within said tube and having a rearwardly extending force-transmitting member attached thereto, said coupling device being adapted to engage an actuating mem'- ber on said hook, a driving member mounted for longitudinal movement with respect to said forearm member, said driving member being pivotally connected at one end to said upper arm component at a point spaced from said elbow hinge, and articulated link means connecting the other end of said driving member to said tube, whereby said wrist unit driven member is turned from 60 to 90 responsive to an angular movement between the forearm member and said upper arm component of approximately 130.

5. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge swingably connecting said forearm member to said upper arm component, a wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member having attachment means at the outer end thereof to receive a hand or hook, said driven member being mounted on said forearm member for turning movement about an axis inclined at an acute angle relative to the forearm centerline, and meansV connected to said upper arm component for turning said driven member responsive to flexion of said forearm member with respect to said upper arm component, said hook or hand being mounted on said driven member at an angle to inclined axis of rotation such that when said forearm member is fully extended, the axis of said hook or hand is substantially parallel to said forearm centerline, the rotation of said driven member about said inclined axis responsive to forearm flexion causing said hook or hand to turn and-swing in a movement combining the motions cf supination, flexion, and abduction.

6. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge swingably connecting said forearm member to said upper arm component, wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member having attachment means at the outer end thereof to receive a hand or hook, said driven member being mounted on said forearm member for turning movement about an axis inclined at an acute angle relative to the forearm centerline, said axis being abducted about the abduction-adduction axis of said wrist unit and being flexed about the flexion-extension axis thereof, and means connected to said upper arm component for turning said drivenr member responsive to flexion of said forearm member with lrespect to said upper arm component, said hook or hand being mounted on said driven member at an angle to said inclined axis of rotation such that when said forearm member is fully extended said hook or hand is in a substantially neutral position about both said flexion-extension and abduction-adduction axes, the rotation of said driven member about said inclined axis responsive to forearm flexion causing said hook or hand to turn and swing in a movement combining the motions of supination, flexion, and abduction.

7. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge swingably connecting said forearm member to said upper arm component, a wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member having attachment means at the outer end thereof to receive a hand or hook, said driven member being mounted on said forearm member for turning movement about an axis inclined at an acute angle relative to the forearm centerline, said axis lying in a plane inclined at an acute angle to the axis of said elbow hinge, and means connected to said upper arm component for turning said driven member responsive to flexion of said forearm member with respect to said upper arm component, said hook or hand being mounted on said driven member at an angle to Said inclined axis of rotation such that when said forearm member is fully extended, said hook or hand is extended about the flexion-extension axis, and is centered between the abducted and adducted-positions, the rotation of said driven member about said inclined axis responsive to forearm flexion causing said hook or hand to turn and swing in a movement combining the motions of supination, flexion, and abduction.

8. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge swingably connecting said forearm member to said upper arm component, a wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member having attachment means at the outer end thereof to receive a hand or hook, said driven member being mounted on said forearm member for turning movement about an axis disposed at an angle of between 10 and 20 to the forearm centerline, said axis being flexed about the flexion-extension axis of said wrist unit and being abducted about the abduction-adduction axis thereof, and means connected to said upper arm component for turning said driven member responsive to flexion of said forearm member with 1 respect to said upper arm component, said hook or hand being mounted on said driven member at an angle to said inclined axis of rotation such that when said forearm member is fully extended, said hook or hand is extended about the flexion-extension axis, and is centered between the abducted and adducted positions, the rotation of said driven member about said inclined axis responsive to forearm flexion causing said hook or hand to turn and swing in a movement combining the motions of supination, flexion, and extension.

9. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge swingably connecting said forearm member to`said upper arm component, a wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member having attachment means at the outer end thereof to receive a hand or hook, said driven member being mounted on said forearm member for turning movement about an axis inciined at an acute angle relative to the forearm centerline, said axis lying in a plane inclined at an angle of approximately 45 to the axis of said elbow hinge and extending in a direction such that said inclined axis is flexed about the flexion-extension axis of said wrist unit and is abducted about the abducton-adduction axis thereof, and means connected to said upper arm component for turning said driven member responsive to exion of said forearm member with respect to said upper arm component, said hook or hand being mounted on said driven member at an angle to said inclined axis of rotation such that when said forearm member is fully extended, said hook or hand is extended about the flexionextension axis, and is centered between the ab ducted and adducted positions, the rotation of said driven member about said inclined axis responsive to forearm flexion causing said hook or hand to turn and swing in a movement combining the motions of supination, flexion, and extension.

10. An artificial arm comprising, in combination, an upper arm component, a forearm member, an elbow hinge swingably connecting said forearm member to said upper arm component, a wrist unit mounted on the outer end of said forearm member, said wrist unit including a driven member having attachment means at the outer end thereof to receive a hand or hook, said driven member being mounted on said forearm member for turning movement about an axis disposed at an angle of between and 20 to the forearm centerline, said axis lying in a plane inclined at an angle of approximately 45 to the axis of said elbow hinge and extending in a direction such that said axis is flexed about the flexionextension axis of said wrist unit and is abducted about the abduction-adduction axis thereof, and means connected to said upper arm component for turning said driven member responsive to flexion of said forearm member with respect to said upper arm component, said hook or hand being mounted on said driven member at an angle to said inclined axis of rotation such that when said forearm member is fully extended, said hook or hand is extended about the flexion-extension axis, and is centered between the abducted and adducted positions, the rotation of said driven member about said inclined axis responsive to forearm flexion causing said hook or hand to turn and swing in a movement combining the motions of supination, flexion, and extension.

GILBERT M. MOTIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 26,378 Selpho et al Dec. 6, 1859 396,061 Allward Jan. 15, 1889 1,042,413 Dorrance Gct. 29, 1912 1,193,969 Aunger Aug. 8, 1916 1,247,077 Caron Nov. 20, 1917 1,465,933 Dedic Aug. 28, 1923 1,475,119 Hulsmann Nov. 20, 1923 1,507,681 Pecorella et a1 Sept. 9, 1924 1,507,682 Pecorella et al Sept. 9, 1924 1,507,683 Pecorella et a1 Sept. 9, 1924 OTHER REFERENCES Publication, Terminal Research Reports on Artificial Limbs, published June 30, 1947, by National Research Council, 2101 Constitution Avenue, N. W., Washington 25, D. C. 

